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UNITED STATES PATENT OFFICE.

F. WALCOTT, OF MILFORD, MASSACHUSETTS, ASSIGNOR TO HIMSELF, AND F. J. COFFIN, OF NEWBURYPORT, MASSACHUSETTS.

BOARD ROOFING.

To all whom it may concern:

Be it known that I, FREEMAN WALCOTT, of Milford, in the county of lVorcester and State of Massachusetts, have invented anew and Improved Roof-Covering, of which the following is a full, clear, and exact description, reference being had to the annexed drawings, in which- Figure l is a perspective view of a roof with my improved covering applied; Fig. 2, a section on the line A, A, of Fig. l; Fig. 3, a section on the line B, B, of Fig. l; Fig. t, a view of one of my prepared boards detached; Fig. 5, detail to be referred to hereafter.

The attempts heretofore made to form a roof covering of a double set of boards breaking joint with each other and placed lengthwise down the slope ofthe roof, have thus far not been attended with success, principally on account of the liability of the boards to warp and also on account of the want of ventilation between the separate courses, and these difficulties have been by no means removed by the device which has sometimes been resorted to offplowing a groove through the center of each board, as the ventilation in such case has been but partial and im erfect and the tendency to warp has soon estroyed the efficiency of the covering.

My invention has for its object to remove entirely both the before mentioned difliculties which I accomplish by covering the whole surface of one side of the boards with grooves, as will now be more fully described.

In Fig. 4 is a view of a board having grooves f plowed upon one of its surfaces. These grooves may extend more or less through the board but I have found about half way through'the board to answer the best purpose. The grooves are placed at a sufficient distance apart to furnish bearings i, care being taken that the joints between the boards of the upper course do not fall immediately over those of the lower course.

When the covering is applied a layer of the grooved boards is first nailed' to the purlins with the grooved surface upmost as at c. A second layer is then secured to these as seen at CZ, in the drawings.

It will be perceived that the grooves f, form a series of channels through the entire roof by which means the most thorough ventilation is secured, and any moisture which may find its way between the two series of boards will be speedil dried through the channels thus furnishec, which to facilitate this operation may be all made to terminate in a longitudinal passage g, beneath the saddle boards. Boards thus grooved are not liable to warp and split as when not thus prepared, and I thus obtain an economical and durable roof covering which possesses the further advantage that it may be applied speedily and in situations where eX- perienced workmen are not at hand.

In lieu of arranging the grooved boards as in Figs. l, and 3, with their grooved surfaces in contact, I sometimes place them as in Fig. 5, the upper layer having the grooves upmost. These grooves thus form channels for the passage of the water from the roof, while those of the lower series furnish the Ventilating channels. Boards prepared as above may be used for the purpose of roofing small projections as in window and door caps or wherever it is required to shed water, and to resist the warping influences of atmospheric changes.

I do not claim making a single groove in the center of roofing boards as this has been done before but I'Vhat I claim as my invention and desire to secure by Letters Patent is A roof covering formed of a double series of boards grooved over their entire surface as set forth for the purpose specified.

FREEMAN WALCOTT. Witnesses:

SAM. COOPER, Trios. L. GLOVER. 

